


The secret of Luffy's sister

by PhoenixLuna



Category: One Piece
Genre: F/M
Language: English
Status: In-Progress
Published: 2020-03-22
Updated: 2020-04-14
Packaged: 2021-02-28 19:53:13
Rating: Not Rated
Warnings: Creator Chose Not To Use Archive Warnings, No Archive Warnings Apply
Chapters: 4
Words: 4,319
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/23262760
Author URL: https://archiveofourown.org/users/PhoenixLuna/pseuds/PhoenixLuna
Summary: Luffy shows up after two years with a young woman. Her name is Monkey D Luna, big sister of Luffy and a pirate. The straw hats are surprised because they did not know about a sister before. Why does she show up now? Where has she been all this time? How comes Luffy never mentioned her? What's her purpose? What crew is she with?
Relationships: Trafalgar D. Water Law/Original Female Character(s)
Comments: 1
Kudos: 11





	1. Chapter 1

**Author's Note:**

  * For [traffyluffy](https://archiveofourown.org/users/traffyluffy/gifts).
  * A translation of [Das Geheimnis um Ruffys Schwester](https://archiveofourown.org/works/22277965) by [PhoenixLuna](https://archiveofourown.org/users/PhoenixLuna/pseuds/PhoenixLuna). 



> Like I said on my other story my English isn't very good because it's not my mother tongue. I will still give my best. Hope you like it.

Luffy and I made our way together to the Sabaody Archipelago to meet his crew again after two years of training break. But as soon as we arrived at the arcipelago, the little chaot left without paying attention to me. Well thanks, that means now I have to find his ship alone. I went to Shakky's bar and maybe Rayleigh was there and could tell me where I could find Sunny. When I arrived at the bar Shakky told me that Ray was not there, which was a real pity, I would have liked to see him again before we set off for the New World. Fortunately Shakky knew where to find Sunny. I decided to leave Ray a letter at the bar because I didn't know if I would run into him again or not. When I went to the Sunny I tried to be as inconspicuous as possible. There were a lot of Marine soldiers in the archipelago. Did the navy already know that Luffy and his crew were here? Actually, I don't think anyone would be that stupid and act too conspicuous, although it is Luffy who magically attracts trouble. Best thing to do is speed it up a little.

After about an hour I arrived at the Sunny where Luffy and his crew were already celebrating their reunion. I jumped on deck and still nobody had noticed me. Slowly I approached Luffy and gave him a headbutt. "Haven't you forgotten something or rather someone?" I asked him. He turned around and looked at me a little guilty before he laughed and scratched the back of his head. "Hey there you are. I was wondering where you'd got to." he laughed and I was busy trying to keep calm so as not to punch him again. The others all looked at me confused. A blond guy, what was his name again Luffy had described them all to me in detail, but it doesn't matter, came up to me with hearts in his eyes and muttered some bullshit. But when he wanted to sniff at me, it was enough for me and I hit him. "Who is this Luffy?" Nico Robin asked. "That's my sister. She'll be travelling with us to the New World." he replied with a grin. "What your sister? You never mentioned you had a sister! Why is she travelling with us? Where has she been all this time?" he was bombarded with questions from that long nose. Luffy was about to start talking when Istopped him. "My name is Monkey D. Luna, and I travel with you to the New World, as Luffy said. That's all you need to know about me." I Saida bit cold. Whether they liked it or not, I didn't care. They all looked at me with very surprised faces. The next moment the navy attacked and everything went relatively fast. The snake princess came to our aid and stopped the navy which we used to dive down and finally made our way to the fishman island. 

When things calmed down a bit I went to my brother. "Luffy, where am I supposed to sleep?" I asked my little brother. "Oh, um, yeah. Franky can you make up a room for Luna somewhere?" Luffy asked the guy who looked like a robot. He nodded and wanted to get to work. "Why should she get her own room? Isn't it enough if he puts a bed in our room for her?" asked the other woman from his crew. "Luna gets her own room!" Luffy stuck to his previous statement. "Thanks kiddo," I said and hugged him. He knew that I liked being alone. After the subject was closed, the others introduced themselves. Sanji and Lysop kept trying to find out more about me. I just ignored them and watched Luffy a little. He had become really strong in the last two years thanks to Ray but was he really ready for the New World? I didn't doubt his strength, but I knew him well enough to know he'll be looking for trouble, he always has been. But it's not only because Luffy often gets into trouble that I was worried about. After all, Blackbeard was in the New World and he could become a great danger to my little brother. 

"This is amazing, isn't it?" Luffy ripped me out of my head. "What do you mean?" I wanted to know because I wasn't sure what he meant. "The ocean. It's everything so amazing," he said. "Oh, that's what you mean. Well, when you saw this already, it's not quite as fascinating as the first time. But I understand what you mean," I told him. "That's right, you've been to Fishman's Island and in the New World. I haven't thought about that," Luffy said. "Do you miss them? Your crew?" he asked after a little while of silence. "Very much. I hope I find them quickly." I admitted truthfully. Yes, I missed them all. For two long years now I was separated from them and that rather involuntarily. "So you want to get out of here fast?" Luffy then asked sadly. I pulled him into a hug. "It probably won't be that quick. I know you don't want me to leave and that you would like me to join your crew, you've asked me to join your crew often enough. But you also know that I miss them and they are my family." I tried to explain to him that I wanted to go back. "So you're a pirate, too. What crew do you belong to?" asked Usopp who came to us and apparently overheard our conversation. Also the others were looking at us curiously now. "Remember what you promised me," I said to Luffy and he nodded knowingly. The question of the long nose I simply left unanswered. I knew it wasn't exactly polite not to tell them more about me but I had my reasons.


	2. Chapter 2

Nami POV.

So Luffy had a sister? How come he never told us? I didn't like the way she was behaving towards us. Could we trust her? "What are you thinking about?" Robin wanted to know. She was standing next to me and probably noticed that I was watching this Luna. "Don't you think this is all a little weird?" I asked her. "Well, yeah, a little. I was with the revolutionary armee during our break and I didn't heard something about that Dragon had a daughter. That's strange," she explained to me and my suspicions grew even more. "I find it strange that she doesn't talk about herself at all. She's so cold and distant from us. Then there is the matter of her own cabin. Not even Luffy as a captain has his own cabin. He sleeps in with the boys so it would have been enough to put a bed in our room. She doesn't seem to want to join us, so why an extra room just for her? But what bothers me most is that I can't find any common ground in the looks. They don't look alike. She has blond hair and blue eyes." I said. "Luffy doesn't look like his father either. Maybe her look comes from her mother," said Robin with an indefinable look on her face. "I think it's weird she won't tell us what crew she's on and we don't even know if she can fight." Usopp got involved in our conversation. It was a fair question. "Luna, can you actually fight?" I wanted to know from her. But she just looked at me and laughed before answering. "You will see if I can or not." I was so upset she didn't give me a decent answer. "What's this stupid question Nami. Of course my sister can fight!" complained our captain. "She was, after all..." but he couldn't get any further because she interrupted him. "Luffy!" only came from her. Luffy said a quick "Sorry." What was it that she didn't want us to know?

Luna POV.

It got really annoying that they couldn't just accept that I don't want to tell them anything about me. There are only a few people who know my whole story. Just as I was about to make an announcement to the navigator, my den-den-mushi, which I had gotten from Rayleigh when he left the island where we were training, rang. Before I accepted the call I walked a little away from the others. "Yes." I answered. "Hello, little one. Have you seen your new wanted poster?" it came from the other end and I could tell by the voice who it was. Rayleigh must have given him the number. Before he could even ask his usual question, I got there first. "No, I'm not joining your crew," I told him, which made him laugh. "I didn't ask you that. Why do you keep turning me down?" he asked sadly. "You know the reason. I've explained it to you often enough. Say what you want and then hang up. Luffy's crew is already getting on my nerves enough," I said, waiting for his answer. "You still with Luffy? Tell him we said hi. Guys this calls for a celebration." I listened, and I was really close to hanging up. "Why is this a reason for celebration now? No, wait, I don't even want to know. You use every little thing as a reason to get drunk anyway. I feel sorry for Ben," I laughed. "Thanks finally someone who understands me," it came from Ben. "Anyway, I just wanted to inform you that your bounty has been raised to 770 million berry and is now read only alive and that your full name is on it and not just the name the navy gave you. They also have a new photo of you on which you can now be easily recognized. So take care of yourself," Shanks explained more seriously. "Oh great as if i haven't already enough trouble. Yes, I know I have to take care of myself, don't you start that too. I'll talk to you soon," I said and hung up. That can't be true. Why was the dead or alive changed to only wlive? Did he has something to do with that? This new picture could be a real problem. On the previous photo you could not see my face because it was covered by the hood of my cape. 

Slowly I went back to the others where Luffy came to me and asked if everything was ok. "Yes everything is fine so far. My bounty has only increased. Oh yeah, greetings from Shanks and his crew." I said to him. "THAT WAS SHANKS?" he suddenly yelled. "Yeah, and don't yell at me like that." "I'd love to have a word with him," he suddenly started pouting. "You will meet him in the New World. He is waiting for you, so be patient." I cheered him up a little, which worked immediately. "You just got off the den-den-mushi with Red Hair Shanks?" Usopp asked excitedly. "Do you mind?" I asked the question. "Did you reject his offer again?" my little brother wanted to know and I just grinned at him which was enough for him to know my answer. "What offer?" Sanji wanted to know. "He wants her in his crew but she refuses every time." Luffy said too fast for me to stop him. Now everyone looked at me in shock. "How... Why refuse such an offer?" came the stammering from Nami. "Simply, I'm already part of a crew." I gave her the only logical answer. "But we're talking about the Yonko Shanks!" came Usopp. "So what?" I just said, and went to Franky. "Can you make the bed about 160x200?" I asked him and he said it was no problem. "If you don't mind me asking, why do you need such a wide bed?" he wanted to know. "Oh, it's just in case Luffy wants to sleep in my room, like when we were little, so it's not too cramped." I told him. I kept to myself that when Luffy woke up after Trafalgar Law operated on him and saved his life, he suffered from nightmares for a long time and didn't want to be alone, so I always slept next to him that he feels safe. I noticed that it was getting restless and went back to the others. Suddenly there was a pirate ship next to ours. The two bubbles touched and a slimy guy jumped on the Sunny and screamed "Kill them all!"

  
  



	3. Chapter 3

Luna POV.

"Kill everyone on the ship!" ordered this slimy bastard. He lands on the ship. "Isn't that Momoo?" Nami said and looked at the giant sea cow who was pulling the other pirates' ship. You could see that the animal was more and more frightened when it saw Luffy's crew. It almost seemed as if she was going through a real bad memory. The sea cow froze and then swam back as if struck by lightning. Out of the corner of my eye I saw Franky approaching us and grabbed this strange guy who didn't even seem to realize that he was alone and his crew was far away. Only when Franky had him firmly under control did he seem to notice this. "Please don't. Just don't throw me into the sea, okay? That's the only thing you can't do! That's no way to deal with other people's lives," he moaned. "You might want to change your tone. After all, you said something about killing everyone," Franky told him. Nami wanted to know who that bastard was. Just as the guy was about to answer, I interrupted him. "Who the hell cares who he is. Just let me handle this, Luffy," I said, looking at my brother, who just nodded and then started grinning. "Cool, maybe I'll finally get to see you use your devil powers." he rejoiced. "You...you have devil powers?" Usopp asked stuttering. "It seems like I have when he say that." he only got an answer and I went up to this slime guy. "So you tried to kill my little brother? Did I get that right?" I asked him. Don't get me wrong I didn't believe that he would be able to hurt my brother neither to kill him but he wanted to try it and that was his big mistake. He shook his head violently and said it was just a misunderstanding. Then he suddenly got big eyes. "I...I know you. I..I just saw your bounty today. You're that angel of death, Monkey D. Luna. There's a 770 million Berry bounty on your head," he stuttered. Of course I did not miss the looks of the others who were looking at me in disbelief. Well, everyone except Luffy. He knew that's what I was called. Only the amount of the bounty might have been new to him but that is not what would shock him, he thinks it is rather cool that it has risen. "Since you apparently know who I am, you must know why the Navy calls me an angel of death, don't you?" I asked him and grinned. How I hated that stupid name. Angel of Death such a stupid name but the Navy was not exactly known for coming up with good names for the pirates. "Please you have to protect me from her." he begged the others, who looked at him confused 

Nami POV. 

So Luffy's sister was called "Angel of Death", but I never heard that name before. But her bounty was very high for the fact that she seemed to be someone unknown. Why was this guy so panicked by her that he even begged us to save him? Could she be dangerous to us? I wonder which crew she belongs to if she has such a high bounty and on the other hand always refuses Shanks offer to join his crew? But I was also upset by the fact that we just learned by chance that she was a devil fruit user. We should know such an important information! What if she had gone overboard? "Why should we protect you from her? You just wanted to kill us! Besides, she can't be that bad when I look at her." Franky wanted to know and this slime guy looked at him in shock. "Wow... do you know who you've got on board here? She's a killer!" yelled this one. A killer? Who did Luffy bring on our ship? Usopp and Chopper looked shocked and frightened at Luna. Could she really be so much different from Luffy when they were brother and sister after all? Luffy had never killed anyone, not even when we were in Ernie's lobby and I was convinced that he hadn't killed anyone even in Marine Ford. "Shihihi Luna when will I see your devil powers?" Luffy laughed. He didn't seem to be bothered or surprised by that statement. "What do you mean by she is a killer?" I wanted to know from the guy. Luna was standing right in front of the guy, grabbing him. Just as the slimeball was about to answer my question, Luna interrupted him. "Enough of this bullshit. You wanted to kill my little brother and I will certainly not let you get away with that. You could never have killed Luffy, but I honestly don't care." she said with an icy cold voice. "Help me now!" he shouted before she put on a devilish grin and threw him into the sea and out of the protective bubble. I was shocked. The guy was right. She was a killer. She threw him into the ocean, stone cold. He was a devil fruit user and he couldn't swim but even if he could have swum he would never have survived to the depth we were at, he wouldn't have had a chance to get to the surface or the water pressure down here would have killed him. "Sorry Luffy but for such a weakling I will not use my devil powers," she said as if nothing had happened and went to Luffy who was sulking slightly. The others also looked at Luna in shock. "Y...y...you killed him!" yelled Usopp. "So what? If he hadn't said he wanted to kill my brother he might have stayed alive," she explained, grinning. "Luffy now say something! Your sister just killed someone!" I yelled at our captain. "Sanji I'm hungry!" he just said, ignoring what his sister had done. Sanji went into the kitchen followed by Luffy who grabbed his sister and pulled her behind him. "She is definitely different from the Captain," said Robin. "Different, you call that? I don't want her here! Who knows what she does to us when we sleep! It is obvious that she can't stand us even though we haven't done anything to her!" I yelled. Could we trust her if she doesn't tell us anything about herself and behaves like this?

****************************************************

Hey everyone! I hope you liked the new chapter. Luna really is different from Luffy. What do you think why is she so much different than Luffy?


	4. Chapter 4

Luffy POV.

When Sanji, after I told him I was hungry, went into the kitchen I grabbed Luna and pulled her along in the same direction. I didn't like the way the others were looking at Luna. She had just done something I would never have done myself but Luna and I were different. From a conversation I overheard between Luna and Rayleigh during training I knew why the Marines called her the Angel of Death. Just like Franky said before, Luna doesn't seem dangerous at first sight, which is why many people underestimate her, but her opponents never survived a fight with her, that's why the Marines called her that. When we arrived in the kitchen I sat down at the counter and watched Sanji cooking something for me. He also seemed to be confused by Luna's action as he did not behave as usual when Nami or Robin were present. "Would you like something to eat?" he asked Luna. "No, I'm not hungry." she said. Sanji looked at her with irritation. He probably thought that since she was my sister, she ate as much as I did. "Is everything okay?" I asked Luna as she seemed very thoughtful. "Yes, everything's fine. That was just a little too easy." she laughed. "Hmm. Did you have to kill him?" I wanted to know from her. I didn't really like what she had done. "You know Luffy. The weak don't get to decide anything, not even how they die." she said in all seriousness. Yeah, I've heard that line before. She said it a lot before. "What's that supposed to mean?" yelled Nami as she entered the kitchen with Robin, Chopper, Usopp and Zoro. Franky and Brook wanted to stay on deck or Franky was probably busy with the room for Luna. "It means exactly what it says. I will gladly repeat it again. The weak don't get to decide anything, not even how they die." Luna replied in an extremely annoyed tone. "I'm out, kiddo." Luna then said in a loving tone and went out on deck.

Luna was annoyed by Nami which she showed her. Nami asked too many questions for Luna's taste. Somewhere I could understand Nami, but I could also understand Luna, she didn't know anybody, so why should she tell everything about herself. Luna was always the closed type who preferred it when others knew as little as possible about her. Why couldn't everyone understand each other? Luna did not show the others her true self which was a sign that she did not trust any of my friends. I was so happy that my sister was with me on the Sunny, but I didn't like the thought that she was only temporarily on board. Why can't she just join my crew? I would love to have her with me. But I could also understand that she wanted to go back to her crew, back to her family. "Your sister is so unlike you. You're like night and day," said Robin who was sitting next to me by now. "Hmm." I just kept saying it because I didn't know what else to say. That we're so different might be because we're not really siblings. Yeah, she had the same name as me, but only because Gramps wanted her to. Luna never liked to hide her real name, but Gramps always said she would be in danger if anyone knew her real name. Even I didn't know it. Only Ace did. He was the one Luna was closest to from the beginning. It was hard not to tell my crew everything, but I promised Luna. That Luna was here now and not with her crew was really all my fault. After the death of Ace I just didn't want to be alone. The planned 3 months shewanted to stay with me became 2 years because I didn't want to let her go and have her with me. This helped my training as Rayleigh said that Luna already had perfect control over her haki. But unfortunately she hadn't used her devil powers once in the two years. When we fought against each other she always used her sword. A sword with a red blade. "You're so lost in thought. I've never seen you like this before," Nami said, tearing me away from my thoughts. "Sorry, I was just thinking about something," I replied. "How long will your sister stay with us?" Nami asked after a short silence. "I don't know. Unfortunately, she wants to get back to her crew as soon as possible. So she will stay until we deliver her to them because I won't let her go looking for them alone," I explained to her and you could see that Nami didn't really like my answer. "What crew does she belong to?" Usopp wanted to know. "Sorry but you'll have to ask her yourself," I replied.

"Does the name Angel of Death mean anything to any of you? I've never heard of her," Nami said. Everyone but Robin and I shook our heads. "Not much is known about her. Until now, the only thing known about the Angel of Death was that she was a New World pirate whose appearance was unknown. On her profile you could not see her face because it was covered by a hood. Also her name and which crew she belongs to was not known. Rumor has it that none of her opponents who saw her face survived. If you believe what this guy said earlier, at least now her appearance and name must have been made known by some event," Robin explained. "And what devil power does she have?" Chopper asked curiously. "I have no idea. I have never seen her use her powers before. When we fought, she only ever used her sword and Haki." I answered Chopper's question. I'd like to know what kind of devil fruit she ate, after all she already had it when Gramps brought Luna to us and said that we had a sister now. "So she fights with a sword?" Zoro wanted to know and participated in the conversation for the first time and he seemed to be curious about this fact. "Yes I do." Luna answered his question which had suddenly entered the room again. "Which one of you is the navigator?" my sister wanted to know and sounded a bit pissed. "Me why?" Nami replied. "Then maybe you should talk less and focus more on your duties as navigator and pay more attention to the course." Luna said in a cold voice. "What's your fucking problem with us?" Nami yelled at my sister. 

**Notes for the Chapter:**

> I know it's unusual for Luffy to be so concerned but he's a little more thoughtful in this story than in the anime/manga. And yes, the quote "The weak don't get to decide anything, not even how they die." is actually from Law but in my story both use that qiote.


End file.
